Ultrahigh Piezoelectric Performance through Synergistic Compositional and Microstructural Engineering

Enhanced Electromechanical Performance in Lead-free (Na,K)NbO3-Based Piezoceramics via the Synergistic Design of Texture Engineering and Sm-Modification

Next-generation electromechanical conversion devices have a significant demand for high-performance lead-free piezoelectric materials to meet environmentally friendly requirements. However, the low electromechanical properties of lead-free piezoceramics limit their application in high-end transducer applications. In this work, a 0.96K0.48Na0.52Nb0.96Sb0.04O3-0.04(Bi0.5-xSmx)Na0.5ZrO3 (abbreviated as T-NKN-xSm) ceramic was designed through phase regulation and texture engineering, which is expected to solve this difficulty. Through our research, we successfully demonstrated the enhanced electromechanical performance of lead-free textured ceramics with a highly oriented [001]c orientation. Notably, the T-NKN-xSm textured ceramics doped with 0.05 mol % Sm exhibited the optimal electromechanical performance: piezoelectric coefficient d33 ≈ 710 pC N-1, longitudinal electromechanical coupling k33 ≈ 0.88, planar electromechanical coupling kp ≈ 0.80, and Curie temperature Tc ≈ 244 °C. Finally, we conducted a detailed investigation into the phase and domain structures of the T-NKN-Sm ceramics, providing valuable insights for achieving high electromechanical properties in NKN-based ceramics. This research serves as a crucial reference for the development of advanced electromechanical devices by facilitating the utilization of lead-free piezoelectric materials with superior performance and environmental benefits.

A Review of Fingerprint Sensors: Mechanism, Characteristics, and Applications

Identification technology based on biometrics is a branch of research that employs the unique individual traits of humans to authenticate identity, which is the most secure method of identification based on its exceptional high dependability and stability of human biometrics. Common biometric identifiers include fingerprints, irises, and facial sounds, among others. In the realm of biometric recognition, fingerprint recognition has gained success with its convenient operation and fast identif ication speed. Different fingerprint collecting techniques, which supply fingerprint information for fingerprint identification systems, have attracted a significant deal of interest in authentication technology regarding fingerprint identification systems. This work presents several fingerprint acquisition techniques, such as optical capacitive and ultrasonic, and analyzes acquisition types and structures. In addition, the pros and drawbacks of various sensor types, as well as the limits and benefits of optical, capacitive, and ultrasonic kinds, are discussed. It is the necessary stage for the application of the Internet of Things (IoT).

Gradient Strain-Induced Room-Temperature Ferroelectricity in Magnetic Double-Perovskite Superlattices

Single-phase multiferroics suffer from a fundamental contradiction between polarity and magnetism in d⁰ electronic configuration, motivating studies of unconventional ferroelectricity in magnetic oxides. However, low critical temperature and polarization still need to be overcome. Here, it is reported that the switchable polarization behavior at room temperature in [(La₂ NiMnO₆ )/(La₂ CoMnO₆ )]_n double-perovskite magnetic superlattice films is achieved by engineering a microstructure with gradient strains, and the ferromagnetic Curie temperature did not show a rapid decrease. The synergy of gradient strains and superlattice components plays a decisive role in inducing ferroelectricity via the tilting or rotation of various oxygen octahedra. Such distortion responses to gradient strains are accompanied by slight magnetic fluctuations, maximizing the preservation of the initial magnetic exchange interactions, which alleviates the contradiction of multiferroic coexistence to a certain extent. This work confirms the room-temperature ferroelectricity in double-perovskite superlattices and provides a preferred strategy for confronting the difficulty of multiferroic coexistence in single-phase materials.

Heterojunction Engineering Enhanced Self-Polarization of PVDF/CsPbBr3 /Ti3 C2 Tx Composite Fiber for Ultra-High Voltage Piezoelectric Nanogenerator

Piezoelectric nanogenerator (PENG) for practical application is constrained by low output and difficult polarization. In this work, a kind of flexible PENG with high output and self-polarization is fabricated by constructing CsPbBr3 -Ti3 C2 Tx heterojunctions in PVDF fiber. The polarized charges rapidly migrate to the electrodes from the Ti3 C2 Tx nanosheets by forming heterojunctions, achieving the maximum utilization of polarized charges and leading to enhanced piezoelectric output macroscopically. Optimally, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits an excellent voltage output of 160 V under self-polarization conditions, which is higher than other self-polarized PENG previously. Further, the working principle and self-polarization mechanism are uncovered by calculating the interfacial charge and electric field using first-principles calculation. In addition, PVDF/4wt%CsPbBr3 /0.6wt%Ti3 C2 Tx -PENG exhibits better water and thermal stability attributed to the protection of PVDF. It is also evaluated in practice by harvesting the energy from human palm taps and successfully lighting up 150 LEDs and an electronic watch. This work presents a new idea of design for high-performance self-polarization PENG.